2.8 Various Commands

C-c C-r

Caesar rotate (aka. rot13) the current message
(message-caesar-buffer-body). If narrowing is in effect, just
rotate the visible portion of the buffer. A numerical prefix says how
many places to rotate the text. The default is 13.

C-c C-e

Elide the text between point and mark (message-elide-region).
The text is killed and replaced with the contents of the variable
message-elide-ellipsis. The default value is to use an ellipsis
(‘[...]’).

This is a format-spec string, and you can use ‘%l’ to say how
many lines were removed, and ‘%c’ to say how many characters were
removed.

C-c M-k

Kill the address under point.

C-c C-z

Kill all the text up to the signature, or if that's missing, up to the
end of the message (message-kill-to-signature).

C-c C-v

Delete all text in the body of the message that is outside the region
(message-delete-not-region).

M-RET

Insert four newlines, and then reformat if inside quoted text.

Here's an example:

> This is some quoted text. And here's more quoted text.

If point is before ‘And’ and you press M-RET, you'll get:

> This is some quoted text.
*
> And here's more quoted text.

‘*’ says where point will be placed.

C-c M-r

Rename the buffer (message-rename-buffer). If given a prefix,
prompt for a new buffer name.

TAB

If message-tab-body-function is non-nil, execute the
function it specifies. Otherwise use the function bound to TAB in
text-mode-map or global-map.